This invention relates to a process for producing C-2 and higher hydrocarbons from lower hydrocarbons, and particularly, direct gas phase electrocatalytic polymerization of lower hydrocarbons, such as methane, to produce higher hydrocarbons, e.g. ethane and gasoline range hydrocarbons.
There remains an interest in the energy industry to produce gasoline range hydrocarbons from natural gas or methane. A series of patents for this purpose where granted to George Olah, i.e. U.S. Pat. Nos. 4,433,192, 4,513,164, 4,465,893 and 4,467,130.
Krist et al. U.S. Pat. No. 5,064,733 describes the electrochemical conversion of CO.sub.2 and CH.sub.4 to C-2 hydrocarbons using a single electrochemical cell. This was accomplished by means of a cell divided by way of a solid electrolyte with methane-containing gas being introduced into one side of the cell and carbon dioxide into the other side of the cell. The process of that patent is primarily concerned with proton conductors used to dimerize methane. The process is operated at quite high temperatures in the order of 600 to 1000 .degree.C. and no H.sub.2 can be produced.
Another process for electrochemically converting methane to C.sub.2 hydrocarbons is described in Hamakawa et al. "Electrochemical Methane Coupling Using Protonic Conductors", J. Electrochem. Soc., Vol. 140, No. 2, February 1993, pp 459-462. This describes the low-level coupling of methane in a cell that includes an electrochemical hydrogen pump. This cell necessarily uses a high temperature proton conductor, SrCe.sub.0.95 Yb.sub.0.05 O.sub.3, as a solid electrolyte, operating at 1173K (900.degree. C.). With this system the evolution of hydrogen and current density were both low. Under an applied potential, the current density was only 1% to fuel conversion and the conversion of CH.sub.4 to high hydrocarbons was less than 1%.
It is the object of the present invention to polymerize and dimerize lower hydrocarbons in order to produce higher hydrocarbons, including unsaturated hydrocarbons.